By "futurephysicist"
Mass Spectrometry is useful for identifying unknown compounds by their unique charge to mass ratio. The compound must be ionized so that electric and magnetic fields will act on the substance. The ion passes through three main components before arriving at the counter. It passes through an acceleration chamber, an electric field and magnetic field, and then a magnetic field. The concept was first introduced in J.J. Thomson's Charge to Mass Ratio experiment.
Ionization occurs when a substance is turned into a gas. A certain amount of energy is passed through the particles in order to make certain molecules lose electrons. These charged particles then enter the next chamber.
In order to accelerate the particles, they are passed through a set of charged parallel plates. The ions are repelled from one plate, and attracted to the other. The ions are accelerated towards a gap in the plate, where they move into the electric field. The velocity of the particle as it exits can be calculated using V=.5mv2/q. An applet to see the effect is found at: http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_massspec1.html
The electric and magnetic field is used to ensure that all ions are travelling at the same speed before the next chamber. The electric field and magnetic field are perpendicular. The goal is to achieve no deflection of the particles. Velocity can also be calculated in this step. v=|E|/B. This is shown at : http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_massspec2.html
The ions then pass through a uniform magnetic field. This field deflects the ions in a circular motion. The ions then travel to a detector, which can identify the substance, based on the radius of the deflection and the velocity and magnetic field. If the radius, velocity and magnetic field are known, the substance’s unique charge to mass ration can be calculated using q/m=v/rB. http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_massspec3.html
Mass Spectrometer
From physick.wikispaces.com
By "futurephysicist"Mass Spectrometry is useful for identifying unknown compounds by their unique charge to mass ratio. The compound must be ionized so that electric and magnetic fields will act on the substance. The ion passes through three main components before arriving at the counter. It passes through an acceleration chamber, an electric field and magnetic field, and then a magnetic field. The concept was first introduced in J.J. Thomson's Charge to Mass Ratio experiment.
Ionization occurs when a substance is turned into a gas. A certain amount of energy is passed through the particles in order to make certain molecules lose electrons. These charged particles then enter the next chamber.
In order to accelerate the particles, they are passed through a set of charged parallel plates. The ions are repelled from one plate, and attracted to the other. The ions are accelerated towards a gap in the plate, where they move into the electric field. The velocity of the particle as it exits can be calculated using V=.5mv2/q. An applet to see the effect is found at: http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_massspec1.html
The electric and magnetic field is used to ensure that all ions are travelling at the same speed before the next chamber. The electric field and magnetic field are perpendicular. The goal is to achieve no deflection of the particles. Velocity can also be calculated in this step. v=|E|/B. This is shown at : http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_massspec2.html
The ions then pass through a uniform magnetic field. This field deflects the ions in a circular motion. The ions then travel to a detector, which can identify the substance, based on the radius of the deflection and the velocity and magnetic field. If the radius, velocity and magnetic field are known, the substance’s unique charge to mass ration can be calculated using q/m=v/rB. http://webphysics.davidson.edu/physlet_resources/bu_semester2/c13_massspec3.html
References